﻿using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Web;

namespace UEditor.Code
{
    enum ResultState
    {
        Success,
        InvalidParam,
        AuthorizError,
        IOError,
        PathNotFound
    }
    public class ListFileManager
    {
        private int Start;
        private int Size;
        private int Total;
        private ResultState State;
        private String PathToList;
        private String[] FileList;
        private String[] SearchExtensions;

        public ListFileManager(string pathToList, string[] searchExtensions)
        {
            this.SearchExtensions = searchExtensions.Select(x => x.ToLower()).ToArray();
            this.PathToList = pathToList;
        }

        public object Result(string start,string size,Config config)
        {
            try
            {
                Start = String.IsNullOrEmpty(start) ? 0 : Convert.ToInt32(start);
                Size = String.IsNullOrEmpty(size) ? config.GetInt("imageManagerListSize") : Convert.ToInt32(size);
            }
            catch (FormatException)
            {
                State = ResultState.InvalidParam;
                return new
                {
                    state = GetStateString(),
                    list = FileList == null ? null : FileList.Select(x => new { url = x }),
                    start = Start,
                    size = Size,
                    total = Total
                };
            }
            var buildingList = new List<String>();
            try
            {
                var localPath = HttpContext.Current.Server.MapPath(PathToList);
                buildingList.AddRange(Directory.GetFiles(localPath, "*", SearchOption.AllDirectories)
                    .Where(x => SearchExtensions.Contains(Path.GetExtension(x).ToLower()))
                    .Select(x => PathToList + x.Substring(localPath.Length).Replace("\\", "/")));
                Total = buildingList.Count;
                FileList = buildingList.OrderBy(x => x).Skip(Start).Take(Size).ToArray();
            }
            catch (UnauthorizedAccessException)
            {
                State = ResultState.AuthorizError;
            }
            catch (DirectoryNotFoundException)
            {
                State = ResultState.PathNotFound;
            }
            catch (IOException)
            {
                State = ResultState.IOError;
            }
            return new
            {
                state = GetStateString(),
                list = FileList == null ? null : FileList.Select(x => new { url = x }),
                start = Start,
                size = Size,
                total = Total
            };
        }

        private string GetStateString()
        {
            switch (State)
            {
                case ResultState.Success:
                    return "SUCCESS";
                case ResultState.InvalidParam:
                    return "参数不正确";
                case ResultState.PathNotFound:
                    return "路径不存在";
                case ResultState.AuthorizError:
                    return "文件系统权限不足";
                case ResultState.IOError:
                    return "文件系统读取错误";
            }
            return "未知错误";
        }
    }
}